Eastern Cape police say they're battling to question a deaf and mute man who allegedly hacked his family to death.

It's believed the 52-year-old man attacked his mother and her four grand-children with an axe.

At the time of his arrest the man was out on bail for the murder of his brother in 2005.

"We are battling to establish a motive for the attack," said the police's Mzukisi Fatyela on Sunday.

"We have found some of the family members who were at home at the time of the incident, but they have been extremely traumatized by the killing of the children and their grandmother."